GSM Optimizer.pdf

NetAct Optimizer 3.1 CD2 for GSM GSM Measurements for Optimizer

For public use – IPR applies 1 © Nokia Siemens Networks

Presentation / PLe / 23.6.2012

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Presentation / PLe/ 23.6.2012

Module Objectives At the end of this module the trainee should be able to: Describe the measurements needed for Optimizer

Outline the measurement setup and collection process



Mobile Measurements The measurements needed in Optimizer How to manage BCCH Allocation List (BAL) changes?

• •

Total FEP measurements

•

CF and DAC measurements if more than 32 BCCH frequencies to be measured

CF and DAC measurements if equal or less than 32 BCCH frequencies to be measured



Data Flow Example Measuring PM database

BSC DX 200

PDE

MMR every 480ms

Optimizer Configurator

Automatic Optimization

C CCMU L S

M

M

OMU

OMU

W C D T U U

W D U

STU

CHU

CM

STU

CHU

CM

Raw data

Interference matrix Configuration data

Algorithm parameters User input

New Plan


CCMU


The usage of mobile measurements in Optimizer Mobile measurements are used in Optimizer • to generate Interference Matrix • to generate timing advance histogram Interference matrix is used for - automatic frequency optimization - automatic adjacency optimization Interference matrices are stored in Optimizer database.



MMR every 480ms

Mobile Measurement Report example



How to Create the Interference Matrix 1. Start the measurements: Either CF (Channel Finder) and DAC (Defined Adjacent Cell) or Total FEP (Frame Erasure Probability) measurements

2.

Retrieve the Interference Matrix to Optimizer database



Mobile Measurements in GSM Defined Adjacent Cell (DAC) measurement collects data from cells defined as adjacent cells. Channel Finder (CF) measurement collects data from nonadjacent cells. Frame Erasure Probability (Total FEP) measurements refers to the estimated probability that a speech frame is erased. Traffic measurements are typically active by default.

The cells that use the same BCCH channel as the serving cell cannot be measured and are defined as Blind Spots.



Mobile measurements BSC

Def adj cell measurements

MMR

Channel finder measurements Calculates FEP values

OPT DB

PM DB

OPTDB_CIP

P_NBSC_CHANNEL_FINDER

OPTDB_ARP

P_NBSC_DEF_ADJ_CELL

OPTDB_FEP

P_NBSC_TOTAL_FEP



Principle of CF and DAC Measurements BSC

BCCH of undefined cells

...and defined adjacent cells BTS

BAL

BAL

BAL

BAL = All BCCH

Active MS

Adjacent cell Non-Adjacent cell



Three Types of Interference Matrices

CF + DAC

FEP For public use – IPR applies 12 © Nokia Siemens Networks

• ARP = Average Received Power • ARP Matrix contains the average received power of each interfering cell. • CIP = C/I Probability • CIP matrix contains the probability that a cell is interfering another cell.

•

FEP = Frame Erasure Probability

Probability that a speech frame is erased.


Measurement Time Minimum measurement period depends on the traffic but should be at least 2-3 days • Less traffic => longer measurement period More measurement rounds means longer measurement time During the measurements and optimization there must be NO CHANGES to the NW



Preparations During the measurements the BCCH Allocation Lists (BALs) need to contain every BCCH frequency in the network Maximum length (theoretical) of the BA list is 32 Common BCCH and WCDMA neighbors will reduce the theoretical maximum BAL length by one each (down to 30) If there are more than 32 (or 31, or 30) BCCH frequencies in the network the measurements need to be run in several cycles of equal length but with different BA lists



How to measure all BCCHs 10

20

25 neighbor cell BCCH frequencies + serving cell frequency

30

(max) 6 free places

If the network has less than 32 BCCHs : create a double BAL If the network has more than 32 BCCHs : rotate the BAL lists



How the measurement information is used? •

•

Step number 1: – Identify the interfering cell the measurement information is related to – In other words: find the cell being the source of the interference Step number 2: – Calculate the interference values – CIP and ARP, or FEP Summarize the information to a matrix

•

These steps are performed by Optimizer

•



Solution: Interference source identification Use distance and antenna bearing to identify the most probable source of the interference

(X, Y) BCCH:x NCC: y BCC: z

(X, Y) BCCH: a NCC: b BCC: c



(X, Y) BCCH: a NCC: b BCC: c

Another Challenge: Blind Spots • After the interference values are calculated and the correct sources of interference is identified, there are still Blind Spots in the interference matrix

• Blind Spots are because of the fact that mobile phones cannot measure the other cells in the same frequency

Cell 1 BCCH: 5

Cell 4 BCCH: 5 Cell 7 BCCH: 9

Cell 2 BCCH: 3 Blind Spot Own Cell



Solution 1: Use Existing Measurements • If the measurement based allocation is not run for the first time it is probable that there is earlier measurement value available between the ”blind spot” cells • Requires that in last time the channels were different

• The measurement based frequency allocation can anyway be run with several measurement periods

Cell 1 BCCH: 5 old channel: 5

Cell 4 BCCH: 5 old channel: 7

Cell 7 BCCH: 9

Cell 2 BCCH: 3 Blind Spot with old value Own Cell



Solution 2: Use Fixed Interference Value • If we populate the interference matrix blind spots with Fixed value => There is then some interference => The same BCCH will not be allocated because the interference => There won’t be Blind Sport in the next iteration

Cell 1 BCCH: 5 New channel: 5

Cell 4 BCCH: 5 New channel: 7

Cell 7 BCCH: 9

Cell 2 BCCH: 3 Some hard coded value Own Cell



Solution 2 (continues) •

The expert user can define some parameters for the solution 2 1. How many closest blind spots are populated with fixed value •

Based on our experience: populating 2-3 closest blind spots is enough (but that is area dependant)

2. What is the fixed value 3. What is the maximum distance of blind spots •


For example if the cells are 100 km away. There is no reason to put anything (else than 0) to interference matrix


How to get the measurements

Less than 32 BCCH frequencies

More than 32 BCCH frequencies

Double BAL for CIP, ARP BAL rotation tool for CIP, ARP MBAL for FEP MBAL for FEP




• •


•





Total FEP - advantages • FEP = Frame Erasure Probability • Maps calculated C/I values to frame erasure probability – => FEP presents better the subjective end-user quality

• Different network scenarios have different mapping tables – E.g. hopping vs. non-hopping networks

• FEP is provided in conjunction with “MBAL” feature – In MBAL object up-to 128 BCCHs can be introduced – All BCCH frequencies are automatically rotated in the BAL – Interval for changing the BAL list is 15 minutes – Adjacent cell BCCH frequencies always measured – MBAL requires “free slots” in BAL ▪ => Number of ADCEs < 31



Principle of Total FEP measurement



Mapping of C/I -> FEP



FEP restrictions It is SAFE To use MBAL if: • Operator only has one GSM BAND • Operator only has channels from PGSM and GSM 1800 band AND in GSM 1800 ARFCNs are within 112 consecutive channel numbers • Operator only has channels from EGSM and GSM 1800 band AND in GSM 1800 ARFCNs are within 112 consecutive channel numbers and channel number 0 is NOT used in EGSM



FEP restrictions It is NOT SAFE To use MBAL if: • Operator has 3 GSM bands in use (PGSM, EGSM and GSM 1800) or • Operator has channel number 0 in use with some other channels from EGSM band or • If the ARFCNs of a band do not fit in 112 consecutive channel numbers

• The bands can be measured one at a time so that only channels from one band are listed in the MBAL • NOTE!! When measuring one band at a time the BTSs from bands that are not measured should be configured NOT to use MBAL For public use – IPR applies 28 © Nokia Siemens Networks


FEP in short 1. Enable TOTAL_FEP_USAGE in BSC (manually with MMLs) 2. Disable CF and DAC measurements in BSC (manually with MMLs) 3. Enable “Meas BCCH Alloc. List Usage” in BTSs (using the MBAL wizard in Optimizer) 4. Create MBAL for BSC (using the MBAL wizard in Optimizer) 5. Start FEP measurements (using the MBAL wizard in Optimizer) 6. Retrieve measurements from PM database



Preparing Nokia GSM IM Creation for FEP (1/21)













For newer BSCs

Creates the plan “FEP ENABLING PLAN“ to CM DB. It needs to be provisioned manually.

For S12 or older BSCs

Creates the MMLs to enable MBAL usage in BTS. MML commands need to be manually executed.






















The MBAL plan is created in OPT DB and needs to be exchanged to CM DB before provisioning.










•Define the weekdays for measurements (for example, Monday, Tuesday). •Define measurement interval in minutes. Use 15-120 minutes interval. •Define the start time and the stop time (00:00 to 24:00). •Additional parameter is restore value and it should be 0.










….
















• •


•





CF and DAC measurements in short Activate the feature “Double BCCH Allocation List” in the BSC

This feature is by default active

Activate the measurement Channel Finder

ZWOC,10,65,00FF;

Activate the measurement Defined Adjacent Cell

ZWOA:2, 626,A;

Start the measurements Channel Finder and Defined Adjacent Cell

Using “Prepare GSM IM Creation” wizard

Retrieve the measurements from PM DB

Optimizer – Tools – Network Statistics – Manage Interference Matrices



Preparing Nokia GSM IM Creation for CIP and ARP (1/15) Select BSCs from the Navigator



Preparing Nokia GSM IM Creation for CIP and ARP (2/15)











































• •


•





CF and DAC measurements in short Activate the feature “Double BCCH Allocation List” in the BSC

ZEQ

Activate the measurement Channel Finder

ZWOC,10,65,00FF;

Activate the measurement Defined Adjacent Cell

ZWOA:2, 626,A;

Start the measurements Channel Finder and Defined Adjacent Cell

Using “Prepare GSM IM Creation” wizard

Retrieve the measurements from PM DB

Optimizer – Tools – Network Statistics – Manage Interference Matrices



Using BAL Rotation (1/18) Select BSCs from the Navigator



Using BAL Rotation (2/18) More than 32 BCCH frequencies to be measured



Using BAL Rotation (3/18) More than 32 BCCH frequencies to be measured



Using BAL Rotation (4/18) To measure more than 32 frequencies using CF and DAC measurements BAL Rotation tool is needed First you must remove old BAL objects if any exist.



Using BAL Rotation (5/18)



Using BAL Rotation (6/18) Start the BAL Rotation tool to begin creating BALs







Settings are user specific




Settings are user specific







•Define the weekdays for measurements (for example, Monday, Tuesday). •Define measurement interval in minutes (1 440 minutes equals 24 hours). •Define the start time and the stop time (00:00 to 24:00). •Additional parameters are I/C thresholds for BSCs (lower=-18, higher=0).






















Using CM Operations Manager provision the backup plan that was created previously (in order to bring back the original configuration in the network).



Exercise 1 (FEP) 1. 2. 3. 4. 5.

Check how many BCCHs are used in your optimization scope Check the version (= release) of the BSCs in your optimization scope Check if the needed features in the BSCs are activated Use Optimizer wizard Prepare Nokia GSM IM Creation to set up and start the measurements In Optimizer, Retrieve the Interference matrix for your scope



Exercise 2 (CIP, ARP) 1. 2. 3. 4. 5.

Check how many BCCHs are used in your optimization scope Check the version (= release) of the BSCs in your optimization scope Check if the needed features in the BSCs are activated Use Optimizer wizard Prepare Nokia GSM IM Creation to set up and start the measurements In Optimizer, Retrieve the Interference matrix for your scope



Document change history Date

Version

Name

Change comment

6.8.2012

1.0

PLe

First version for OPT 3.1 CD2

25.1.2013

2.0

PLe

Valid for Optimizer 3.1 CD2 PCD



GSM Optimizer.pdf

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